Zero Stuffing is the process of placing zero-valued coefficients between a filter's existing coefficients to increase the filter's sampling frequency.

Another operation, Zero Padding, is the process of prepending and/or appending zero-valued coefficients to a filter to increase the number of coefficients. (For reasons of computational efficiency in implementing decimating and interpolating FIR filters, filters are sometimes Zero Padded to make the number of coefficients a multiple of the change in sampling frequency.) Since the new coefficients are zero, the filter's frequency response is unaffected.

The Zero Stuff and Zero Pad dialog allows you to do these either or both of these operations.

To Zero Stuff the filter, specify one or more zeros to be stuffed between each coefficient. You can also specify whether the sampling frequency will be automatically scaled. (If you stuff N zeros between coefficients, the sampling frequency increases by a factor of N+1, because there are now N+1 times as many coefficients. For example, stuffing three zeros increases the sampling frequency by a factor of four.)

To Zero Pad the filter, specify the number of coefficients to prepend and/or append. Prepended zeros are added before the original coefficients, and appended zeros are added after the orignial coefficients. (Tip: when padding, it is generally preferable to append, because prepending will increase the filter's delay.)